CVD apparatuses and methods of forming a layer over a semiconductor substrate

ABSTRACT

The invention includes a method of forming a layer on a semiconductor substrate that is provided within a reaction chamber. The chamber has at least two inlet ports that terminate in openings. A first material is flowed into the reaction chamber through the opening of a first of the inlet ports. At least a portion of the first material is deposited onto the substrate. The reaction chamber is purged by flowing an inert material into the reaction chamber through the opening of a second of the inlet ports. The inert material passes from the opening and through a distribution head that is positioned within the reaction chamber between the first and second openings. A second material can then be flowed into the chamber through an opening in a third inlet port and deposited onto the substrate. The invention also includes a chemical vapor deposition apparatus.

CROSS REFERENCE TO RELATED APPLICATION

This patent is a divisional of patent application Ser. No. 09/932,711,filed Aug. 17, 2001 now U.S. Pat. No. 6,677,250.

TECHNICAL FIELD

The present invention pertains to CVD apparatuses and methods forforming layers over a semiconductor substrate.

BACKGROUND OF THE INVENTION

Methods of chemical vapor deposition (CVD) are used to produce thinlayers of material during various industrial processes includingsemiconductor device fabrication. CVD methods involve introduction ofvaporized precursor materials into a reactor, adsorption of the vaporprecursor materials onto a surface of a semiconductor substrate andeventual incorporation of such precursor materials into solid films.

Sequential introduction of various precursors into a CVD apparatus mayresult in undesirable mixing of precursors in areas of the apparatusother than on the semiconductor substrate, such as within a commonsupply line or within the chamber itself. The first precursor materialis purged from the chamber after adsorption onto the semiconductorsubstrate and prior to introduction of a second precursor material toavoid undesirable mixing.

In conventional CVD processes incomplete purging may occur due toprecursor material becoming trapped within an area of the reactionchamber. Such incomplete purging may result in unwanted mixing ofprecursor materials upon the introduction of the second precursor andmay lead to adsorption of precursor materials and adduct formation uponreaction chamber surfaces. Adduct materials that form on the reactionchamber surfaces may precipitate onto the substrate and cause defects inthe thin layer formation.

Accordingly it is desirable to provide CVD apparatuses and depositionmethods that are designed to minimize unwanted mixing and unwanteddeposition of films onto apparatus surfaces.

BRIEF DESCRIPTION OF THE DRAWING

Preferred embodiments of the invention are described below withreference to the following accompanying drawing.

The FIGURE shows a diagram of a deposition chamber and a related processchemical delivery system according to an embodiment of the presentinvention.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a method of forming a layer ona semiconductor substrate. A semiconductor substrate is provided withina reaction chamber. The chamber has at least two inlet ports extendingtherein. A first of the at least two inlet ports terminates in a firstopening which is a first distance from the substrate. A second of theinlet ports terminates in a second opening which is a second distancefrom the substrate. The second distance is greater than the firstdistance. A first material is flowed into the reaction chamber throughthe first inlet port. At least a portion of the first material isdeposited onto the substrate to form the layer over the substrate. Thereaction chamber is purged by flowing an inert material into thereaction chamber through the second inlet port.

In another aspect, the invention encompasses a method of chemical vapordeposition. A substrate is provided within a reaction chamber. Thereaction chamber includes a lid. The reaction chamber also includes afirst valve assembly and a second valve assembly. Each valve assemblyincludes a valve closure. The reaction chamber also includes an inertmaterial inlet port which is distinct from the valve assemblies. Thefirst and second valve assemblies, as well as the inert material inletport pass through the lid of the reaction chamber. A first material isflowed into the chamber through the first valve closure, and at least aportion of this first material is deposited onto the substrate. Thereaction chamber is purged by flowing an inert material through theinert material inlet port. The inert material passes through the inertmaterial inlet port and through a distribution head. The distributionhead is positioned within the reaction chamber between the lid and thefirst and second valve closures. Once the first material has beendeposited, a second material is flowed into the chamber through thesecond valve closure. At least a portion of the second material isdeposited onto the substrate.

In another aspect the invention encompasses a chemical vapor depositionapparatus. The apparatus includes a deposition chamber and a substrateplatform. Two or more inlet ports extend into the deposition chamber. Afirst of the inlet ports terminates in a first opening which is a firstdistance from the substrate platform. A second of the inlet portsterminates in a second opening that is a second distance from thesubstrate platform. The second distance is greater than the firstdistance. The apparatus also includes a porous distribution head withinthe chamber located between the first and second openings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

The present invention is described with reference to the FIGURE. Amethod of forming a layer 12 over a semiconductor substrate 10 is shown.The semiconductor substrate 10 is provided within an apparatus 8comprising a reaction chamber 14. The reaction chamber 14 has at leasttwo inlet ports 16 and 20. A first of the at least two inlet ports 16terminates in a first opening 18 a first distance from the substrate. Asecond of the at least two inlet ports 20 terminates in a second opening22 a second distance from the substrate. A first material 32 is flowedinto the reaction chamber 14 through the first inlet port 16. At least aportion of first material 32 is deposited onto substrate 10 to form alayer 12.

An inert material 34 is flowed into the reaction chamber through thesecond inlet port 20 to purge the reaction chamber. The flowing of theinert material can occur while flowing the first material.Alternatively, flowing the inert material may occur after deposition ofthe first material or both during and after deposition of the firstmaterial. The flow of inert material can be pulsed or continuous. It isadvantageous to continuously flow the inert material while flowing thefirst material to assist in moving the first material away from the areaof the chamber around first inlet port 16 and reduce adduct formation onreaction chamber surfaces. It is also advantageous to purge the chamberby flowing the inert material from an opening located a greater distancefrom the substrate than the opening through which the first material isprovided to reduce, or even minimize retention of first material withinthe reaction chamber.

The inert material 34 preferably comprises a fluid that is inert toreaction with the substrate 10, with the first material 32, and withmaterials subsequently introduced into the chamber for deposition. Theinert material can comprise a gas. Exemplary gases can be helium, argonor nitrogen or mixtures thereof. Preferably when the inert material 34comprises a gas, the gas is flowed into the chamber at a rate no greaterthan about 100 standard cubic centimeters per minute (sccm).

The second inlet port 20 can be behind the porous distribution head 38.The distribution head 38 can be located within the reaction chamber 14between the first opening 18 and the second opening 22. It isadvantageous to provide the inert material from behind a porousdistribution head where the distribution head is positioned between thefirst and the second openings to result in a downward flow of inertmaterial. The downward flow can both minimize counter-flow of the firstmaterial and assist in the diffusion of the first material over thesubstrate. In addition, the downward flow can alleviate unwantedadsorption of first material onto surfaces within the reaction chamber.

After deposition of the first material 32, a second material 36 can beflowed into the reaction chamber. The second material 36 is flowed intoreaction chamber 14 through a third inlet port 24. The third inlet port24 terminates in a third opening 26 which is a third distance from thesubstrate 10. The second distance is greater than the third distance. Atleast a portion of the second material 36 is deposited onto thesubstrate 10. It is advantageous to flow the second material through aninlet port that is distinct from the inlet port through which the firstmaterial passes rather than through a common inlet port because unwantedmixing of the first and second materials within an inlet port is therebyminimized. It is to be understood, however, that the methods describedherein may be adapted to processes that provide a first material and asecond material through a common inlet port.

While flowing the second material, the reaction chamber may again bepurged by flowing an inert material through the second inlet port asdescribed above. Alternatively, the inert material may be flowed afterflowing the second material or both during and after the flowing of thesecond material. A series of multiple rounds of deposition of reactivematerials onto the substrate, accompanied either by a simultaneousflowing or by a subsequent flowing of inert material through of thereaction chamber according to the method described herein, arecontemplated in the present invention.

Numerous chemicals can be utilized for first material 32 and for secondmaterial 36 for purposes of the present invention. Exemplarycombinations include a first material comprising trimethyl aluminum anda second material comprising one or both of water and ozone; or a firstmaterial comprising TiCl₄ where the second material comprises ammonia;or a first material comprising Ta₂O₅ where the second material comprisesammonia.

A second aspect of the invention encompassing a method of chemical vapordeposition is described with reference to the FIGURE. A substrate 10 isprovided within a reaction chamber 14. The reaction chamber 14 includesa lid 40, a first valve assembly 42 having a first valve closure 28, anda second valve assembly 44 having a second valve closure 30. An inertmaterial inlet port 20 is provided into the reaction chamber 14, theinert material inlet port 20 being distinct from the valve assemblies 42and 44. In this aspect of the invention, one, two or all three of thefirst valve assembly 42, the second valve assembly 44 and the inertmaterial inlet port 20 can pass through the lid 40. A first material 32is flowed into the reaction chamber 14 through the first valve closure28. At least a portion of the first material 32 is deposited onto thesubstrate 10.

After the first material 32 is deposited onto the substrate 10, thereaction chamber 14 and the valve closures 28, 30 are purged by flowingan inert material 34 through the inert material inlet port 20 into thereaction chamber. Alternatively, inert material 34 can be flowed throughthe reaction chamber while flowing first material 32. The inert material34 is passed from the inert material inlet port 20 through adistribution head 38. The distribution head 38 is within the reactionchamber 14 and between the lid 40 and the first and second valveclosures. The purging of the reaction chamber and valve closures canutilize, for example, a distribution head 38 that is a gas dispersionhead in combination with an inert material 34 comprising a gas. Theinert material is removed from the reaction chamber through an outletport 48.

After deposition of first material 32, a second material 36 can beflowed through the second valve closure 30 into the reaction chamber 14.At least a portion of the second material 36 is deposited onto thesubstrate 10. Inert material 34 can be flowed into the reaction chambersimultaneously with the flowing of the second material, can be flowedafter the flowing of the second material, or can be flowed both duringand after the flowing of the second material.

Still referring to the FIGURE, chemical vapor deposition apparatus 8includes a deposition chamber 14 and a substrate platform 46. Theapparatus 8 includes at least two inlet ports 16 and 20, and at leastone outlet port 48, that extend into the chamber 14. A first of the atleast two inlet ports 16 terminates in a first opening 18. There is afirst distance between the substrate platform 46 and the first opening18. A second of the at least two inlet ports 20 terminates in a secondopening 22. There is a second distance between the substrate platform 46and the second opening 22. The second distance is greater than the firstdistance. The at least one outlet port 48 terminates in an opening 50.The apparatus 8 can also include a porous distribution head 38 withinthe chamber 14. The porous distribution head 38 is positioned betweenthe first opening 18 and the second opening 22.

The shown apparatus 8 includes a lid 40. The first inlet port 16, or thesecond inlet port 20, or both can pass through the lid, and in the shownembodiment, inlet ports 16 and 20 both pass through the lid. Inalternative embodiments, at least one of the inlet ports can access thechamber through an area of apparatus 8 other than through the lid. Forinstance, one or more of inlet ports 16 and 20, may pass through achamber wall.

Outlet port 48 can access the chamber though the lid or through areas ofapparatus 8 other than the lid. It is advantageous for the outlet portto access the chamber through a surface opposing the surface throughwhich at least the second inlet port 22 passes to assist in maintainingdirectional flow of precursor gas away from the surface through whichthe second inlet port passes. A directional flow can aid in removal ofreactive materials from the reaction chamber and thereby reduce orminimize adduct formation on surfaces near the second inlet port andother surfaces within the reaction chamber.

The porous distribution head 38 of the apparatus 8 is not limited to aspecific size and may, for example, extend across less than the entirelength of the chamber 14. One example of a distribution head which maybe utilized in the present invention is a gas dispersion head.

The porous distribution head 38 of the present invention is not limitedto a specific material but may comprise, for example, aluminum such asanodized aluminum. In addition, the size of the distribution head pores39 and the distance between the pores are not limited to specificvalues. An exemplary pore diameter is about 0.040 inches. The distancebetween the pores of the distribution head may be measured by thedistance between the center point of one pore and the center point of aneighboring pore. For purposes of this invention, this center to centerdistance between pores can be, for instance, a distance of not greaterthan about 0.100 inches.

In addition to the features described above, an apparatus encompassed bythe present invention may also include a third inlet port 24. The thirdinlet port 24 terminates in a third opening 26 which is a third distancefrom the substrate platform 46. The third distance is less than thesecond distance. In the shown embodiment, the third inlet port 24 passesthrough the lid 40 of apparatus 8, but can also enter the chamber thoughan alternative area of the apparatus such as a chamber wall.

The distance between the first opening and the substrate platform (thefirst distance) and the distance between the third opening and thesubstrate platform (the third distance) are not limited to specificvalues. The first and the third distance can be equal. Either the firstdistance or the third distance or both are preferably from about 28 mmto about 30 mm.

The second inlet port 22 of the apparatus can be located behind theporous distribution head 38. The distribution head 38 is within thereaction chamber 14 and between the first opening 18 and the secondopening 22 and, in embodiments comprising a third inlet port, alsobetween the second opening 22 and the third opening 26.

The inlet ports encompassed by the present invention are not limited toany specific form. One or more of the inlet ports in the apparatus maybe comprised by a valve assembly 42 and 44. Further, a valve assemblycan comprise a valve closure 28, 30. The valve closure is not intendedto be limited to a specific mechanism and can be, for instance, locatedat an opening that terminates an inlet port 18, 26, such closure beingcapable of sealing access from the respective inlet port into thereaction chamber 14.

An apparatus configuration wherein the inert material is flowed frombehind a porous distribution head, the distribution head being fartherfrom the substrate than the valve closure, is advantageous because thedownward flow of inert material can assist in preventing counter-flow offirst and second materials into the opposite valve.

In the shown embodiment, valve assemblies 42 and 44 pass through the lid40. Alternatively, one or both of the valve assemblies can access thechamber through other areas of the apparatus 8. For instance, one orboth of the valve assemblies can pass though the chamber wall.

The advantages conferred by the present invention can make the inventionparticularly suitable for processes where an efficient purge isnecessary to prevent unwanted mixing of reactive chemicals and adductformation upon exposed surfaces within a reaction chamber. Suchprocesses include atomic layer deposition.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A chemical vapor deposition apparatus comprising: a depositionchamber; a substrate platform; at least two inlet ports extending intothe chamber, a first of the at least two ports terminating in a firstopening a first distance from the substrate platform and a second of theat least two inlet ports terminating in a second opening a seconddistance from the substrate platform, the second distance being greaterthan the first distance; a porous distribution head within the chamberand between the first and second openings; a lid; and wherein the firstinlet port passes through the lid.
 2. The apparatus of claim 1 whereinthe first distance is from about 28 mm to about 30 mm.
 3. The apparatusof claim 1 wherein the porous distribution head comprises pores having adiameter of about 0.040 inches and having a center to center distance ofnot greater than about 0.100 inches.
 4. The apparatus of claim 1 whereinthe porous distribution head comprises aluminum.
 5. The apparatus ofclaim 1 wherein the porous distribution head comprises a gas dispersionhead.
 6. The apparatus of claim 1 wherein the porous distribution headextends across less than the entire length of the chamber.
 7. A chemicalvapor deposition apparatus comprising: a deposition chamber; a substrateplatform; at least three inlet ports extending into the chamber, a firstof the at least three inlet ports terminating in a first opening a firstdistance from the substrate platform, a second of the at least threeinlet ports terminating in a second opening a second distance from thesubstrate platform, and a third of the at least three inlet portsterminating in a third opening a third distance from the substrateplatform, the second distance being greater than the first distance andgreater than the third distance; at least one outlet port extending intothe chamber, said outlet port terminating in a fourth opening; a lid;wherein the second inlet port is behind a porous distribution head, saiddistribution head being within the reaction chamber and between thefirst and second openings and between the second and third openings; andat least one of the first or third inlet ports passes through the lid.8. The apparatus of claim 7 wherein the first and third inlet ports passthrough the lid.
 9. The apparatus of claim 8 wherein the second inletport passes through the lid.
 10. The apparatus of claim 8 wherein theoutlet port does not pass through the lid.
 11. The apparatus of claim 8further comprising a first valve assembly and a second valve assembly,wherein the first valve assembly comprises the first inlet port and afirst valve closure, said first valve closure being positioned at thefirst opening; and wherein the second valve assembly comprises the thirdinlet port and a second valve closure, said second valve closure beingpositioned at the third opening.
 12. The apparatus of claim 11 whereinat least a portion of the first valve assembly and at least a portion ofthe second valve assembly pass through the lid.